Two-Layer Battery Anode Structure for Silicon Volume Change
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Solution Overview
Problem
The existing negative electrodes for secondary batteries face challenges in achieving high capacity and efficient charge/discharge performance due to the limitations of carbon-based materials, particularly with silicon-based materials experiencing volume changes that disrupt the conductive path during charge/discharge processes.
Innovation Solution
A negative electrode with a two-layer structure is developed, comprising a first mixture layer with silicon oxide and a needle-type carbon-based conductive material, and a second mixture layer with a carbon material and sphere-type carbon-based conductive material, which enhances the binding force and maintains conductivity during volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative electrode active material to increase capacity, then theoretical capacity increases 10 times compared to carbon-based material, but volume change rate reaches 300% or more causing conductive path disconnection
Solution Approach 1:
The silicon-based particles are embedded within a three-dimensional conductive network formed by needle-type carbonaceous material, creating a nested structure where the carbon network surrounds and supports the silicon particles. This allows the silicon to expand and contract during charge/discharge cycles while maintaining continuous electrical contact through the surrounding carbon matrix, preventing conductive path disconnection despite 300% volume changes.
Solution Approach 2:
The needle-type carbonaceous material acts as an intermediary between silicon-based particles, providing a stable conductive framework that mediates the volume changes. The carbon material forms a flexible three-dimensional network that accommodates silicon expansion/contraction while maintaining electrical connectivity, serving as a buffer and conductive bridge throughout the charge/discharge process.
2Quantity of substance
If silicon-based material is used to achieve high capacity, then energy density increases, but charge/discharge efficiency decreases to about 80% compared to 92% for carbon-based material
Solution Approach 1:
The conductive material is not uniformly distributed but specifically arranged as a three-dimensional network with needle-type carbonaceous material strategically positioned around silicon particles. This localized conductive architecture ensures efficient electron transport pathways are created exactly where needed at the silicon-carbon interfaces, optimizing charge/discharge efficiency while maintaining high capacity.
Solution Approach 2:
The negative electrode uses a composite structure combining silicon-based particles with needle-type carbonaceous material in a three-dimensional network configuration. This composite design leverages the high capacity of silicon while the carbon network provides efficient electron conduction pathways, achieving both high energy density and improved charge/discharge efficiency compared to pure silicon electrodes.
3Ease of manufacture
If conventional single-layer negative electrode structure is used, then manufacturing is simple, but it is difficult to maintain conductive path during volume changes and achieve high capacity
Solution Approach 1:
The conductive network transitions from conventional two-dimensional planar structures to a three-dimensional spatial network using needle-type carbonaceous material. This dimensional advancement creates conductive pathways in multiple directions and planes, forming a robust three-dimensional framework that maintains electrical connectivity during silicon volume changes, significantly improving conductive path stability while remaining manufacturable.
Solution Approach 2:
The three-dimensional conductive network is designed with dynamic flexibility to accommodate the expanding and contracting silicon particles during charge/discharge cycles. The needle-type carbonaceous material forms a flexible framework that can deform and reconfigure while maintaining continuous electrical pathways, adapting to the dynamic volume changes of silicon without breaking conductive connections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration increases battery capacity while preventing structural deterioration and improving cycle characteristics by maintaining the conductive path and binding force between active materials, leading to enhanced charge/discharge efficiency and capacity retention.
Implementation Method 1
the first mixture layer includes a first carbon material and a silicon oxide as a first active materials in a weight ratio of 90 to 99 : 1 to 10 and a first needle type carbon-based conductive material as a first conductive material
Implementation Method 2
This configuration increases battery capacity while preventing structural deterioration and improving cycle characteristics by maintaining the conductive path and binding force between active materials
Data Source
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AI summary
The technology relates to a negative electrode for a secondary battery, and a secondary battery including same. The negative electrode comprises a composite material layer having a double-layer structure, but includes silicon oxide and carbon nanotubes in only one layer, such that it is possible to increase the capacity of a battery while preventing structural deterioration of the negative electrode due to changes in electrode volume during charging and discharging.